This invention concerns a photo detector adjustment device which adjusts the photo detector in optical disk players and other optical heads.
Generally photo detectors are adjusted in three axial directions.
In other words, there is adjustment in a plane perpendicular to the optic axis and adjustment of the direction of the optic axis. The adjustment in the plane perpendicular to the optic axis is performed to position an optical spot properly on the photo detector. The adjustment in the direction of the optic axis is performed so that offset is not generated when the optical spot focal point dislocation which accompanies disk changes is detected during focal point detection.
A conventional device for the adjustment of photo detectors in optical disk players and other optical heads is shown in FIG. 5. Reference numeral 7 designates a semiconductor laser which is the light source for the optical head. Reference numeral 8 is a half prism which forks the optical path. 9 is a collimitor lens which transforms diffused light into parallel light or parallel light into converging light. 10 is an object lens which converges light. 11 is a holder. 12 is a cylindrical lens contained in the holder for the detection of optical spot focal dislocation on the disk (not shown). 13 is a laser beam.
The adjustment of the optical spot on the photo detector 1 is divided into biaxial adjustment moving the photo detector 1 in plane X-Z perpendicular to the optic axis, and Y axis direction adjustment moving the holder 11 containing the cylindrical lens 17 in the direction of the Y, or optic, axis.
Because the conventional device for the adjustment of photo detectors has the structure mentioned above, the optical spot on the photo detector 1 must be adjusted by repeatedly alternating the biaxial adjustment moving the photo detector 1 in plane X-Z perpendicular to the optic axis, and Y axis direction adjustment moving the holder 11 containing the cylindrical lens 12 in the direction of the Y, or optic, axis. The amount of time this takes is a problem.